Methods and apparatus for pumping coolant to an energy delivery device

ABSTRACT

Apparatus and methods for delivering coolant to an energy delivery device used to treat tissue with electromagnetic energy. A cooling system includes a pump that is configured to pump a coolant to the energy delivery device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/725,562, filed Aug. 31, 2018, the content of which is fullyincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The invention generally relates to apparatus and methods for deliveringcoolant to an energy delivery device used to treat tissue withelectromagnetic energy.

BACKGROUND

Certain types of energy delivery devices are capable of treating apatient's tissue with electromagnetic energy. These energy deliverydevices, which emit electromagnetic energy in different regions of theelectromagnetic spectrum for tissue treatment, may be used to treat amultitude of diverse skin conditions. For example, the energy deliverydevice may non-ablatively and non-invasively treat a skin condition orother type of tissue condition.

One variety of these energy delivery devices emits high frequencyelectromagnetic energy in the radio-frequency (RF) band of theelectromagnetic spectrum. The high frequency energy may be used to treatskin tissue by passing high frequency energy through a surface of theskin, while actively cooling the skin to prevent damage to the skin'sepidermal layer closer to the skin surface. The high frequency energyheats tissue beneath the epidermis to a temperature sufficient todenature collagen, which causes the collagen to contract and shrink and,thereby, tighten the tissue. Treatment with high frequency energy alsocauses a mild inflammation. The inflammatory response of the tissuecauses new collagen to be generated over time (between three days andsix months following treatment), which results in further tissuecontraction.

Typically, energy delivery devices include a treatment tip that isplaced in contact with, or proximate to, the patient's skin surface andthat emits electromagnetic energy that penetrates through the skinsurface and into the tissue beneath the skin surface. The non-patientside of the energy delivery device, such as an electrode for highfrequency energy, in the treatment tip may be sprayed with a coolant orcryogen spray. Heat is conducted from the warmer tissue to the coolertreatment tip, which cools tissue to a shallow depth beneath the skinsurface. A controller may trigger the coolant spray based upon anevaluation of the temperature readings received as feedback fromtemperature sensors in the treatment tip.

The cryogen spray may be used to pre-cool superficial tissue beforedelivering the electromagnetic energy. When the electromagnetic energyis delivered, the superficial tissue that has been cooled is protectedfrom thermal effects. The target tissue that has not been cooled or thathas received nominal cooling will warm up to therapeutic temperaturesresulting in the desired therapeutic effect. The amount or duration ofpre-cooling can be used to select the depth of the protected zone ofuntreated superficial tissue. After the delivery of electromagneticenergy has concluded, the cryogen spray may also be employed to preventor reduce heat originating from treated tissue from conducting upwardand heating the more superficial tissue that was cooled before treatmentwith the electromagnetic energy.

Previous devices used, and relied upon, a heated reservoir to providepressurized cryogen. A heated reservoir may require a large amount oftime to startup or recover after replacing a spent cryogen canister.Indeed, users are often forced to wait several minutes while the cryogensystem is pressurized when the system is powered on or after a freshcanister of cryogen is installed.

Although conventional methods and apparatus for delivering cryogensprays have proved adequate for their intended purpose, what is neededare improved methods and apparatus for delivering a coolant, such as acryogen, to the treatment tip.

SUMMARY

In an embodiment, a method for treating tissue beneath a skin surfacewith electromagnetic energy includes pumping a fluid from a container toan energy delivery device configured to emit the electromagnetic energy.

In an embodiment, an apparatus for treating tissue beneath a skinsurface with electromagnetic energy includes an energy delivery deviceconfigured to deliver the electromagnetic energy to the tissue and acooling system with a pump configured to pump a coolant or cryogen tothe energy delivery device.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification and in which like reference numerals refer tolike features, illustrate embodiments of the invention and, togetherwith a general description of the invention given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a diagrammatic view of a treatment system with a handpiece, atreatment tip, a console, and a generator.

FIG. 2 is a perspective view of an assembly consisting of an embodimentof the handpiece and treatment tip for use with the treatment system ofFIG. 1.

FIG. 3 is an exploded view of the assembly of FIG. 2.

FIG. 4 is a rear view of an assembled treatment tip showing an electrodeand temperature sensors.

FIG. 5 is an exploded view of the treatment tip of FIG. 4 in which thetreatment electrode is shown in an unfolded condition.

FIG. 6 is a schematic diagram of a cryogen supply system.

DETAILED DESCRIPTION

Referring now to the drawings, FIGS. 1-5 describe a treatment apparatus10 that generally includes a handpiece 12, a treatment tip 14 that maybe coupled in a removable and releasable manner with the handpiece 12, aconsole generally indicated by reference numeral 16, and a systemcontroller 18. The system controller 18, which is incorporated into theconsole 16, orchestrates the global operation of the differentindividual components of the treatment apparatus 10. Under the controlof the system controller 18 and any operator interaction with the systemcontroller 18 at the console 16 and with controls at the handpiece 12,the treatment apparatus 10 is adapted to deliver electromagnetic energyin a high frequency band of the electromagnetic spectrum to a region ofa patient's tissue. The electromagnetic energy, which may be deliverednon-invasively and non-ablatively, heats the tissue to a targetedtemperature range. The elevation in temperature may produce for example,changes in collagen fibers that achieve a desired treatment result, suchas removing or reducing wrinkles and otherwise tightening the skin tothereby improve the appearance of a patient 20 receiving the treatment.

The treatment tip 14 may provide, either alone or in combination withthe handpiece 12, an energy delivery member that includes a treatmentelectrode 24. In a representative embodiment, the treatment electrode 24may be arranged on a flexible circuit that includes anelectrically-insulating substrate 30 composed of a non-conductivedielectric material and a region 28 composed of an electrical conductorcarried on the electrically-insulating substrate 30. Theelectrically-insulating substrate 30 may include a contact side 32 thatis placed in contact with the skin surface and a non-contact side 34that is opposite from the contact side 32. The conductor region 28 ofthe treatment electrode 24 is physically carried on the non-contact side34 of the substrate 30 and is therefore separated by the substrate 30from the skin surface during treatment.

The substrate 30 of the flexible circuit may include a thin flexiblebase polymer film with thin conductive leads or traces 49. Some of theleads 49 may electrically couple the conductor region 28 with one ormore contact pads 57. The base polymer film of substrate 30 may be, forexample, polyimide or another material with a relatively high electricalresistivity and a relatively high thermal conductivity. The traces 49and contact pads 57 may contain copper or another conductorcharacterized by a relatively high electrical conductivity. The traces49 and contact pads 57 may be formed by depositing a layer of theconductor on the substrate 30 and patterning the conductor layer withlithography and etching processes. Instead of the representative singleconductor region 28, the conductor region 28 may be segmented intoplural individual electrodes that can be individually powered tosequentially deliver electromagnetic energy to the tissue.

The treatment electrode 24 is electrically coupled through the traces 49and contact pads 57 by a set of insulated and shielded conductors 22that extend from the handpiece 12 to the generator 26 at the console 16.The generator 26 is configured to generate the electromagnetic energyused in the treatment to impart a therapeutic effect by heating targettissue beneath the patient's skin surface. The generator 26, which mayhave the form of a high frequency power supply, is equipped with anelectrical circuit operative to generate high frequency electricalcurrent, typically in the radio-frequency (RF) band of theelectromagnetic spectrum. The electrical circuit in the generator 26converts a line alternating current voltage into drive signals for thetreatment electrode 24. The drive signals have parameters (e.g., energycontent and duty cycle) appropriate for the amount of power and the modeof operation that have been selected by the treating clinician. Inalternative embodiments, the treatment apparatus 10 may be configured todeliver energy in the infrared band, microwave band, or another highfrequency band of the electromagnetic spectrum, rather than within theRF band, to the patient's tissue.

The system controller 18 include at least one processor 23 coupled to amemory 25. The at least one processor 23 may represent one or moremicroprocessors, and the memory 25 may represent the random accessmemory (RAM) comprising the main storage of system controller 18, aswell as any supplemental levels of memory, e.g., cache memories,non-volatile or backup memories (e.g., programmable or flash memories),read-only memories, etc. In addition, memory 25 may be considered toinclude memory storage physically located elsewhere in system controller18, e.g., any cache memory in a processor 23, as well as any storagecapacity used as a virtual memory, e.g., as stored on a mass storagedevice 27 or another computer (not shown) coupled to system controller18 via a network.

System controller 18 also typically receives a number of inputs andoutputs for communicating information externally. For interface with auser or operator, system controller 18 typically includes one or moreuser input devices (e.g., a keyboard, a mouse, a trackball, a joystick,a touchpad, a keypad, a stylus, and/or a microphone, among others) inthe form of a user interface 29. The user interface 29 may be used todeliver instructions to the system controller 18 to adjust the generator26 and to establish treatment settings based upon operator input at thehandpiece 12. System controller 18 may also include a display 31 (e.g.,a CRT monitor or an LCD display panel, among others).

System controller 18 operates under the control of an operating system33, and executes or otherwise relies upon various computer softwareapplications, components, programs, objects, modules, data structures,etc. In general, the routines executed by the system controller 18 tooperate the treatment apparatus 10, whether implemented as part of anoperating system or a specific application, component, program, object,module or sequence of instructions, will be referred to herein as“computer program code.” The computer program code typically comprisesone or more instructions that are resident at various times in variousnon-transitory memory and storage devices in a computer, and that, whenread and executed by one or more processors in a computer, causes thatcomputer to perform the steps necessary to execute steps or elementsembodying the various aspects of the operation of the treatmentapparatus 10.

The system controller 18 includes digital and/or analog circuitry thatinterfaces the processor 23 with the generator 26 for regulating thepower delivered from the generator 26 to the treatment electrode 24.Generator software 35 resides as an application (i.e., program code) inthe memory 25 and is executed by the processor 23 in order to issuecommands that control the operation of the generator 26. The systemcontroller 18 includes digital and/or analog circuitry that interfacesthe processor 23 with a cryogen supply 65, described more fully below,for regulating the cryogen delivered to the treatment electrode 24.Cryogen software 37 resides as an application (i.e., program code) inthe memory 25 and is executed by the processor 23 in order to issuecommands that control the operation of the cryogen supply 65.

During a tissue treatment involving the treatment electrode 24, thesubstrate 30 is arranged between the conductor region 28 and the skinsurface of the patient. Electromagnetic energy may be transmitted in atranscutaneous manner from the conductor region 28 through the thicknessof substrate 30 and across the surface area of the portion to the tissueby capacitively coupling with the tissue of the patient 20.

As best shown in FIG. 4, the treatment tip 14 includes temperaturesensors 44, such as thermistors, that are located on the non-contactside 34 of the substrate 30 that is not in contact with the patient'sskin surface. Typically, the temperature sensors 44 are arranged aboutthe perimeter of the conductor region 28 of the treatment electrode 24.Temperature sensors 44 are constructed to detect the temperature of thetreatment electrode 24 and/or treatment tip 14, which may berepresentative of the temperature of the treated tissue. The temperaturesensors 44 are electrically coupled by the conductive traces 49 with thecontact pads 57, which are used to supply direct current (DC) voltagesfrom the system controller 18 through the electrical wiring to thetemperature sensors 44. The measured temperature reflects thetemperature of the treated tissue and may be used as feedback in acontrol loop controlling energy delivery and/or cooling of the skinsurface. The treatment tip 14 may also include pressure sensors (notshown) for detecting physical contact between the treatment electrode 24and the skin surface of the patient 20.

An activation button 36, which is accessible to the operator from theexterior of the handpiece 12, is configured to be actuated to close aswitch in a normally open circuit with the generator 26. The closedcircuit energizes the treatment electrode 24. Actuation of theactivation button 36 triggers delivery of the high frequency energy overa short timed delivery cycle to the target tissue. After a fixed amountof time has elapsed, the delivery of high frequency energy from thetreatment electrode 24 to the tissue at the treatment site isdiscontinued. In a stamping mode of operation, the handpiece 12 ismanipulated to position the treatment tip 14 near a different treatmentsite on the skin surface and another cycle of high frequency energy isdelivered to the patient's tissue. This process may be repeated for anarbitrary number of treatment sites.

High frequency electrical current flowing between the treatmentelectrode 24 and the patient 20 is concentrated at the skin surface andthe underlying tissue across the contacting surface area of the portionof the treatment electrode 24. Capacitive coupling of the high frequencyelectromagnetic energy relies on energy transfer from the conductorregion 28 through the dielectric material of the substrate 30 to createan electric field across the surface area where the treatment electrode24 contacts the patient's body. The time-varying electric field induceselectrical currents within the surrounding tissue beneath the skinsurface.

Because of the natural resistance of tissue to electrical current flow,volumetric heating results within the tissue. The volumetric heatingdelivers a therapeutic effect to the tissue near the treatment site. Forexample, heating to a temperature of 50° C. or higher may contractcollagen, which may result in tissue tightening or another aestheticeffect to improve the patient's appearance. The heating depth in thetissue is based upon the size and geometry of the treatment electrode 24and, contingent upon the selection and configuration of the treatmenttip 14, can be controlled to extend from a few hundred micrometersbeneath the skin surface to several millimeters.

A non-therapeutic passive return electrode 38 is used to electricallycouple the patient 20 with the generator 26. During patient treatment,the high frequency current flows from the treatment electrode 24 throughthe treated tissue and the intervening bulk of the patient 20 to thereturn electrode 38 and then to the generator 26 through conductorsinside a return cable 40 to define a closed circuit or current path 42.The return electrode 38 is physically attached by, for example, anadhesive bond to a site on the body surface of the patient 20, such asthe patient's back.

The surface area of the return electrode 38 in contact with the patient20 may be relatively large in comparison with the surface area of thetreatment electrode 24. Consequently, at the tissue adjacent to thereturn electrode 38, the current density flowing from the patient 20 tothe return electrode 38 is relatively low in comparison with the currentdensity flowing from the treatment electrode 24 to the patient 20.Because negligible heating is produced at its attachment site to thepatient, a non-therapeutic effect is created in the tissue adjacent tothe return electrode 38.

Although the treatment electrode 24 and the return electrode 38 arerepresentatively configured for the delivery of monopolar high frequencyenergy, the treatment electrode 24 may be configured to deliver bipolarhigh frequency energy. The modifications to the treatment apparatus 10required to deliver bipolar high frequency energy are familiar to aperson having ordinary skill in the art. For example, the returnelectrode 38 may be eliminated from the treatment apparatus 10 and abipolar type of treatment electrode substituted for the monopolartreatment electrode 24.

With continued reference to FIGS. 1-5, the handpiece 12 is constructedfrom a housing 46 that includes a body 48, a cover 50 assembled byconventional fasteners with the body 48, and an electrical/fluidinterface 52 for the treatment tip 14. The housing 46 may be fabricatedby an injection molding process using a suitable polymer resin as aconstruction material. The body 48 and cover 50 constitute shell halvesthat are integrally fastened together as an assembly. The housing 46encloses an interior cavity 54 bounded on one side by an interiorsurface of the body 48 and bounded on the other side by an interiorsurface of the cover 50. After the body 48 and cover 50 are assembled,the handpiece 12 has a smoothly contoured shape suitable for grippingand manipulation by an operator. The operator maneuvers the treatmenttip 14 and treatment electrode 24 to a location proximate to the skinsurface and, typically, to place the treatment electrode 24 in acontacting relationship with the skin surface.

The housing 46 includes a nose 56 and a window 58 in the nose 56 that issized for the insertion and removal of the treatment tip 14. Theelectrical/fluid interface 52 is disposed between the window 58 and theinterior cavity 54 enclosed inside the housing 46. The treatment tip 14is sized to be inserted through the window 58 and configured to bephysically engaged with the handpiece 12, as described below. In theengaged state, the contact pads carried on the substrate 30 of thetreatment electrode 24 establish respective electrical connections withcomplementary electrical contacts 60 (FIG. 3), such as pogo pins,carried by the electrical/fluid interface 52 of the handpiece 12. Theseelectrical contacts 60 are electrically coupled with one or more of theconductors 22 that extend from the handpiece 12 to the generator 26 andsystem controller 18. Treatment electrode 24 is at least partiallyexposed through the window 58.

The handpiece 12 may include a control panel 62 and a display 64 thatmay be carried by the cover 50. The control panel 62 may include variouscontrols, such as controls 69, 70 used to respectively increase andreduce the treatment setting and controls 71, 72 that respectivelyenable and disable the controls 69, 70. The display 64 may be used todisplay information including, but not limited to, energy delivered,tissue impedance, duration, and feedback on procedure technique. Theavailability of the information displayed on the display 64 mayconveniently eliminate the need to display identical information at theconsole 16 or may duplicate information displayed at the console 16. Bydisplaying information at the handpiece 12, the operator can focus onthe procedure without diverting his attention to glance at informationdisplayed by the display on the console 16. In one embodiment, thedisplay 64 may constitute a thin, flat liquid crystal display (LCD)comprised of a light source or reflector and an arbitrary number ofcolor or monochrome pixels arrayed in front of the light source orreflector. A driver circuit (not shown) is provided to control theoperation of the display 64.

The treatment tip 14 includes a rigid outer shell 66 and a nipple 34that is coupled with the open rearward end of the outer shell 66 tosurround an interior cavity. A fluid delivery member 41 is configured asa control valve to deliver a spray of a cryogen or similar coolant froma nozzle 39 onto the electrode 24. Extending rearwardly from a centralfluid coupling member 32 is a conduit 45 having a lumen defining a fluidpath that conveys a flow of the coolant to the nozzle 39. The coolant ispumped from a coolant supply (FIG. 6) through tubing that ismechanically coupled with a fitting 47 formed on the nipple 34 andhydraulically coupled with the lumen of the conduit 45.

The electrode 24 is exposed through a window 51 defined in a forwardopen end of the outer shell 66. The electrode 24 may be formed as aconductive feature on a substrate 30, which in a representativeembodiment of the invention is a flexible sheet of dielectric materialwrapped about a forward end of a support member 53. The rearward end ofthe support member 53 includes a flange 55 used to couple the supportmember 53 to the nipple 34. The flexible substrate 30 is wrapped orfolded about the support member 53 such that the contact pads 57 areexposed through slots 59 defined in the nipple 34. A support arm 67bridges the window 51 for lending mechanical support to the flexiblesubstrate 30.

The treatment tip 14 includes openings 68 defined on diametricallyopposite sides of the outer shell 66. The openings 68 are used totemporarily secure the treatment tip 14 with the handpiece 12 in advanceof a patient treatment procedure. A line 63 extends through the interiorcavity 54 inside the housing 46 of handpiece 12. The line 63 isconnected with the fluid delivery member 41 and the line 63 is furtherconnected by a line 61 with the cryogen supply 65.

One purpose of the cryogen spray is to pre-cool the patient's epidermis,before powering the treatment electrode 24, by heat transfer between thetreatment electrode 24 and the skin surface. The cooling creates areverse thermal gradient in the tissue such that the temperature of thetissue at and near the skin surface is cooler than the temperature ofthe tissue deeper within the epidermis or dermis. As a result, the highfrequency energy delivered to the tissue fails to heat all or a portionof the patient's epidermis to a temperature sufficient to causesignificant epidermal thermal damage. Depths of tissue that are notsignificantly cooled by pre-cooling will warm up to therapeutictemperatures, which cause a desired therapeutic effect. The amountand/or duration of pre-cooling may be used to select the protected depthof untreated tissue. The cryogen delivered by the fluid delivery member41 may also be used to cool portions of the tissue during and/or afterheating by the high frequency energy transferred from the treatmentelectrode 24. Post-cooling may prevent or reduce heat delivered deeperinto the tissue from conducting upward and heating shallower tissueregions, such as the epidermis, to temperatures which could thermallydamage shallower tissue regions even though external energy delivery tothe targeted tissue has ceased.

Various duty cycles of cooling and heating that rely on cooling and highfrequency energy transfer from the treatment electrode 24 are utilizedcontingent upon the type of treatment and the desired type oftherapeutic effect. The cooling and heating duty cycles may becontrolled and coordinated by operation of the system controller 18 andfluid delivery member 41. Suitable cryogens include low boiling pointfluids, but are not limited to, R134a (1,1,1,2-tetrafluoroethane)refrigerant, liquid nitrogen, HFO-1234ze (1,3,3,3-tetrafluoropropene)refrigerant, and R152a (1,1-difluoroethane) refrigerant. Heat can beextracted from the treatment electrode 24 by virtue of evaporativecooling of the cryogen, which lowers the temperature of the treatmentelectrode 24.

Referring now to FIG. 6, the cryogen supply 65 may include a pump 76, amanifold 80, a line 92 coupling the manifold 80 with the pump 76, amanifold 98, a line 94 coupling the manifold 98 with the pump 76, and aline 61 that extends from the console 16 to the handpiece 12. The pump76 and manifolds 80, 98 may be housed at the console 16 of the treatmentapparatus 10.

A canister 78 of cryogen is placed in fluid communication with thecanister manifold 80 and is at least partially surrounded by a heater82. The canister manifold 80 may include a muffler 84 and a pressuresensor 86 that are tapped into the internal fluid paths inside themanifold 80. The canisters 78 are prefilled with given volume ofcryogen. When a canister 78 of cryogen is consumed and replaced withanother canister 78 filled with cryogen, muffler 84 may function as anexhaust that allows the release of any residual pressure that might bepresent at or near the canister manifold 80. During operation of thecryogen supply 65, the canister 78 is heated to a selected temperatureby heat energy transferred from the heater 82 to increase the internalpressure of the cryogen to a selected pressure or value. In someembodiments, the selected temperature is a temperature selected by auser that will result in an increase in the internal pressure of thecryogen and may vary depending upon the identity of the cryogen, aswould be understood by a person having ordinary skill in the art. Thesystem controller 18 may rely on pressure readings from the pressuresensor 86 as feedback in a closed-loop control system to control theoperation of the heater 82 and thereby the internal pressure inside thecanister 78. The temperature and pressure of the cryogen inside thecanister 78 may be maintained at lower values than conventional becauseof the introduction of the pump 76 into the fluid path leading from thecanister 78 to the handpiece 12. Conventionally, the heating of thecryogen in the canister 78 is used to increase fluid pressure of thecryogen in the canister 78 and thereby pressurizes the lines leadingfrom the canister 78 to the handpiece 12. In contrast, because the pump76 provides the primary source of fluid pressurization, the temperatureof the cryogen in the canister 78 can be reduced to maintain a loweredpressure inside the canister 78 than conventional. The loweredtemperature and pressure keeps the contained cryogen in a liquid stateinside the canister 78 and the fluid line 92 leading to the pump 76 andprevents vapor development from cryogen vaporization.

Downstream from the canister manifold 80, a filter 88 in fluid line 92may be used to remove contaminants that might be introduced uponreplacing the cryogen canister 78. Contaminants may include human hair,skin, dust, dust mites, and other undesired material.

During replacement of the cryogen canister 78, the check valve 90 influid line 92 may be used to prevent the back flow of pressurizedcryogen from downstream locations to the manifold 80 and loss throughthe muffler 84. During typical operation of the cryogen supply 65, thecheck valve 90 is moved to an open configuration by the fluid pressureof the cryogen in the portion of the line 92 between the check valve 90and manifold 80; but during replacement of the cryogen canister 78, thecheck valve 90 moves to a closed position as the cryogen pressurizationis absent. In this way, any cryogen contained in the cryogen supply 65downstream of check valve 90 is confined and not lost.

The pump 76 may increase pressure of a liquid cryogen cooling systemrapidly and precisely. By increasing or maintaining pressure of theliquid cryogen cooling system, the cryogen may remain in a liquid stateuntil released to ambient conditions. The pump 76 operates to create apressure differential between the line 92, which is at a comparativelylow nominal pressure during operation, and the line 94, which is at acomparatively high nominal pressure during operation. In conventionalcryogen supplies, all of the lines leading from the canister to thehandpiece are maintained at the comparatively high pressure and none ofthese lines is maintained at the comparatively low pressure because, atleast in part, the heating of the canister 78 provides pressurization ofthe cryogen. In an embodiment, the pump 76 may be a diaphragm pump. Adiaphragm pump is a positive displacement pump that uses a combinationof the reciprocating action of a diaphragm and suitable valves on eitherside of the diaphragm to pump the cryogen.

Typical pressures upstream of the liquid pump 76 may range from about 50psi to about 80 psi, inclusive, or from about 60 psi to about 70 psi,inclusive, or about 61 psi, about 62 psi, about 63 psi, about 64 psi,about 65 psi, about 66 psi, about 67 psi, about 68 psi, about 69 psi, orany fractional part thereof. Typical pressures downstream of the liquidpump 76 may range from about 110 psi to about 130 psi, inclusive, orfrom about 115 psi to about 125 psi, inclusive, or about 116 psi, about117 psi, about 118 psi, about 119 psi, about 120 psi, about 121 psi,about 122 psi, about 123 psi, about 124 psi, or any fractional partthereof. In alternative embodiments, typical pressures downstream of theliquid pump 76 may range from about 100 psi to about 130 psi, inclusive,or from about 105 psi to about 125 psi, inclusive, or about 106 psi,about 107 psi, about 108 psi, about 109 psi, about 110 psi, about 111psi, about 112 psi, about 113 psi, about 114 psi, about 115 psi, about116 psi, about 117 psi, about 118 psi, about 119 psi, about 120 psi,about 121 psi, about 122 psi, about 123 psi, about 124 psi, or anyfractional part thereof. The pump 76 may provide instantaneous or nearinstantaneous pressurization of the lines 61, 94, which contrasts withthe significant time delays that are experienced when relying onconventional heating of the cryogen canister to provide pressurizationof the cryogen. The faster pressurization by the pump 76 may speed theperformance of a patient treatment using the treatment apparatus 10. Thepump 76 may also provide tighter control over the pressure in the lines61, 94 such that the pressure is maintained in a narrower range thanpossible with conventional canister heating.

Optionally, a check valve 96 may be installed in the line 94 between thepump 76 and the manifold 98. The check valve 96 may prevent the pump 76from experiencing a backpressure condition.

The manifold 98 may include a pressure sensor 100, an arrestor 102, andone or more relief valves 104. The arrestor 102 may function to minimizepressure surges that may be a byproduct of the operation of the pump 76.For instance, if the pump 76 is a diaphragm pump, reciprocating volumedisplacement may cause intermittent surge of cryogen with each expansionand contraction of the diaphragm and the arrestor 102 may dampen theseintermittent surges. The relief valves 104 may be configured to open ifthe internal pressure in the manifold 98 exceeds some selected value,such as an unsafe maximum value.

As described above, the lines 61, 63 connect the manifold 98 to acontrol valve 74 providing the fluid delivery member 41, which is acomponent of the handpiece 12, through a fitting 106. The pressure inthe line 63 is maintained at the elevated pressure present in the line94. The fitting 106 may permit the handpiece 12 to be connected to thecryogen supply 65 and disconnected from the cryogen supply 65.

References herein to terms such as “vertical,” “horizontal,” etc. aremade by way of example, and not by way of limitation, to establish aframe of reference. It is understood that various other frames ofreference may be employed for describing the invention without departingfrom the spirit and scope of the invention. It is also understood thatfeatures of the invention are not necessarily shown to scale in thedrawings. Furthermore, to the extent that the terms “composed of,”“includes,” “having,” “has,” “with,” or variants thereof are used ineither the detailed description or the claims, such terms are intendedto be inclusive and open-ended in a manner similar to the term“comprising.”

It will be understood that when an element is described as being“attached,” “connected,” or “coupled” to another element, it can bedirectly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is described asbeing “directly attached,” “directly connected,” or “directly coupled”to another element, there are no intervening elements present.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

While the invention has been illustrated by a description of variousembodiments and while these embodiments have been described inconsiderable detail, it is not the intention of the applicant torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. Thus, the invention in its broader aspects istherefore not limited to the specific details, representative apparatusand method, and illustrative example shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of applicant's general inventive concept.

What is claimed is:
 1. A method for treating tissue beneath a skinsurface with electromagnetic energy, the method comprising: pumping afluid from a container to an energy delivery device configured to emitthe electromagnetic energy, wherein the container is coupled with amanifold and a pressure sensor is tapped into the manifold; heating thefluid inside the container to a selected temperature, wherein the fluidis maintained in a liquid state inside the container; and providingclosed-loop control over the heating of the fluid based on pressurereadings from the pressure sensor.
 2. The method of claim 1 wherein thefluid is pumped from the container to the energy delivery device using adiaphragm pump.
 3. The method of claim 2 wherein the fluid is pumpedfrom the container to the energy delivery device using a first lineupstream of the diaphragm pump and a second line downstream of thediaphragm pump, the first line is at a first pressure, and the secondline is at a second pressure.
 4. The method of claim 3 wherein the firstpressure is in a range from about 50 psi to about 80 psi, and the secondpressure is in range from about 110 psi to about 130 psi.
 5. The methodof claim 3 wherein the second pressure is greater than the firstpressure.
 6. The method of claim 1 wherein the fluid is pumped from thecontainer to the energy delivery device using a diaphragm pump, thediaphragm pump is coupled to the container by a fluid line, and thefluid is also maintained under pressure in a liquid state inside thefluid line.
 7. The method of claim 1 wherein the fluid is a coolant. 8.The method of claim 7 wherein the energy delivery device includes anelectrode, and further comprising: delivering a spray of the coolantfrom a nozzle onto the electrode.
 9. The method of claim 1 furthercomprising: delivering the electromagnetic energy from the energydelivery device to treat the tissue beneath the skin surface.
 10. Anapparatus for treating tissue beneath a skin surface withelectromagnetic energy, the apparatus comprising: a heater; a containerconfigured to hold a coolant, the container at least partially enclosedin the heater; an energy delivery device configured to deliver theelectromagnetic energy to the tissue; a manifold coupling the containerwith a fluid line; a cooling system including a pump configured to pumpthe coolant to the energy delivery device, the pump coupled to thecontainer by the fluid line; a system controller communicatively coupledto the energy delivery device and to the cooling system, the systemcontroller programmed to control operation of the pump and the heater tomaintain the coolant in a liquid state inside the container; and apressure sensor communicatively coupled to the system controller, thepressure sensor coupled with the manifold, and the pressure sensortapped into the manifold, wherein the system controller is configured tocontrol the operation of the heater and the pump based on pressurereadings from the pressure sensor.
 11. The apparatus of claim 10 whereinthe system controller is programmed to control the operation of theheater and the pump to maintain the coolant in the liquid state insidethe fluid line.
 12. The apparatus of claim 10 wherein the energydelivery device includes an electrode, a nozzle, and a control valveconfigured to control delivery of the coolant from the nozzle to theelectrode.
 13. The apparatus of claim 12 wherein the pump is a diaphragmpump.
 14. The apparatus of claim 13 further comprising: a manifoldarranged between the pump and the control valve, the manifold includingan arrestor configured to respond to pressure surges from operation ofthe diaphragm pump.
 15. The apparatus of claim 12 wherein the energydelivery device is configured to emit the electromagnetic energy fromthe electrode.
 16. The apparatus of claim 10 further comprising: a firstcheck valve in the fluid line.
 17. The apparatus of claim 16 furthercomprising: a second check valve in the fluid line.
 18. The apparatus ofclaim 14 further comprising: a check valve in the fluid line.